Ultra high frequency oscillator



Dec. 31, 1946. Q MCCARTHY 2,413,364

ULTRA HIGH FREQUENCY OSCILLATOR Filed 'June 12, 1943 2 Sheets-Sheet 1INVENTOR Henry cl [W'ar/zy ATTORNEY De. 31, 1946. J, MCCARTHY ULTRA HIGHFREQUENCY OSCILLATOR '2 Sheets-Sheet 2 Filed June 12,.1943

ATTORNEY Patented ec. 31, 1946 ULTRA HIGH FREQUENCY OSCELLATOR Henry J.McCarthy, Danvers, Mass, assignor to Sylvania Electric Products Inc.,Salem, Mass, a corporation of Massachusetts Application June 12, 1943,Serial No. 490,703

2 Claims.

This invention relates to electrical oscillation devices with particularreference to ultra his frequency or short wave oscillations.

An object of this invention is to provide improved means for supportingshort wave electrical oscillations, and method of making said means.

Another object is to provide means, in an oscillator, for maintainingthe oscillation wavelength at an effectively constant value despitetemperature variation.

Other objects, advantages, and features will be apparent from thefollowing specification taken in conjunction with the accompanyingdrawings in which:

Figure 1 is a perspective view of a tube embodying this invention;

Figure 2 is an exploded view of the structure of Figure 1; and

Figure 3 is a section View, in part, of the structure of Figure 1,illustrating the oscillatory circuit.

The general nature of the device embodyin this invention is that of atube for the generation of electrical short waves, having metal platesas part of an oscillation circuit, and grids mounted on the plates.

An important disadvantage in a tube of this nature has been theundesirable change in wavelength produced by the effect of heatvariation on the plates. Dimensional or positional change in the platesor parts thereof, as a result of heat variation, tended to change thecapacitance or inductance, or both, in the oscillation circuit, withresultant undesirable tendency to change the wavelength.

Another disadvantage has been that grids mounted on the plates beforethe sealing of the plates in the walls of the envelope, were liable tobe damaged by, or collect impurities during, the .91

sealing operation.

This invention obviates the above disadvantages by so forming the platesthat heat variation causes opposing tendencies of movement therein andthe wavelength is efiectively maintained at a constant value; and bysealing the plates in the glass envelope without the grids and providinggrid assemblies and means for removably mounting them on the plates,whereby the grids may be mounted on the plates after the sealingoperation of the plates to the glass envelope has been completed.

The illustrative embodiment of this invention as shown in the drawingsprovides a tube base I; a glass envelope having a lower portion 2, acentral portion 3, and an upper portion 4; electrodes 5 and 6 forsupporting an electron flow therebetween within the glass envelope; anda pair of metal plates l and 3 which are hermetically sealed in thewallof the glass envelope and which separate the portions 2 and 3 and 4' of;he envelope wall.

An oscillatory circuit is provided by the plates 1 and 8 and theirconnection housing 9 outside the glass envelope as the inductance, andthe separation of the plates 7 and 8 with-in the envelope as thecapacitance.

The flow of electrons between the lectrodes 5 and 6 past the plates 1and 8 sets up oscillations in the oscillatory circuit. Theseoscillations are picked up by the lead H3 and provide short electricalwaves.

Ordinarily, heat variation in the plates 1 and 8, brought about throughthe operation of the tube, would so affect the plates 1 and 8 as to varythe gap therebetween and consequently the capaciance of the circuit, aswell as to vary the dimensions of the plates and the connection housingand consequently the inductance of the circuit. This action wouldundesirably change the wavelength provided by the circuit.

The plates 1 and 8 are provided with annular portions H and I2respectively, formed to counteract and effectively neutralize thetendency of heat variation to change the wavelength of the oscillatorycircuit.

Plates 1 and 8 also have turned lips l3 and M respectively, definingcentral cylindrical openings in which grid units [5 and I6 are mounted,being held by clips struck from the plates, as at I! in plate 8.

Plates 1 and 8 are further provided with peripheral flanges l8 and I9which define annular sections 26 and 2| to which the glass portions 2,3, and 4 of the glass envelope arehermetically sealed. The flanges I8and I9 provide a seat for the annular connection housing 9, as at 22 and23.

The pick up loop 24 of the lead It extends within the cavity formedoutside the glass envelope between the plates I and 8 and within theconnection housing 9.. The sleeve 25 through which the pick up lead HIextends, provides a second pick up lead.

The action of the temperature variation compensation arrangement isillustrated in Figure 3. With the metal plate I anchored to the glassenvelope parts 2 and 3, the normal tendency, under the action of heat,is for the lip 13 to move in the direction of arrow 21. The formation ofthe annular portion 1 l of plate 7 as a depression in opposition to thedirection of the lip l3 causes the central portion of the plate 1 tomove bodily in the direction of the arrows 28, under the action of heat,and thus counteract and neutralize the movement of the lip l3.

It is desirable to slightly more than counteract the movement of the lip[3 to ofiset the effect of the dimensional change in the peripheralportions of the plates I and 8, and in .the connection housing 9.

Thus through similar arrangement of the annular portion l2 of the plate8, the relation between the inductance and capacity of the oscillatorycircuit remains such that the resultant wavelength is effectivelymaintained constant under the action of heat variation.

In assembling the tube of this invention the glass envelope portions 2,3 and 4 are sealed to the plates 1 and 8 while the bottom of portion 2and the top of portion 4 are open, and without the grid units [5 and IE.

When the sealing in of the plates 1 and 8 has been completed, the gridunits I5 and 16 are {mounted on the plates 1 and 8 and clamped in placeas by clips I1, and thereafter the glass por- 4 an electron flowtherebetween; a pair of annular metalplates-between saideiectrodes,spaced therefrom and extending through the wall of said envelope andhaving spaced, aligned, lipped openings through which said electron flowmay pass within said envelope, each of said plates having a concentricannular depression therein within the envelope and between said envelopeand the inner edge of said annular plate to counteract the movement ofsaid lipped openings under heat variation; a grid in each of saidopenings; and an electrical connection between said plates and outsidesaid envelope.

2. An electrical short wave generator tube comprising a hermeticallysealed glass envelope, a pair of electrodes in said envelope forsupporting an electron flow therebetween, a pair of annular metal platesextending through the wall of said envelope and having spaced, alignedopenings within said envelope in line with the path of said electronflow, each of said plates having a turned lip on its edge within saidenvelope, and each of said plates having a depression therein within theenvelope to counteract the movement of said lips under heat variation, agrid assembly removably held in each of said openings by spaced clips onthe respective plates, each assembly comprising a grid support and agrid mounted therein, and an electrical connection between said platesand outside said envelope.

HENRY J. MCCARTHY.

